Portable computer with low power CD-player mode

ABSTRACT

A method for controlling a peripheral device in a computer system by a user that requires the CPU of the computer to be powered-on for only the short period of time needed for the CPU to translate a user-specified command into a command that the CPU then transmits to the peripheral device. Inputs are added to the computer system for direct input of user commands to the peripheral device. The BIOS power-up/reset routine of the computer is modified to detect power-on as a result of user input to the added inputs, to then transmit a corresponding command to the peripheral device, and to finally power down the CPU. The system controller of the computer is electrically shielded from the peripheral device when the system controller is powered-down and the peripheral device is operating.

TECHNICAL FIELD

The present invention relates to the control of peripheral devices in acomputer system, and, in particular, the control of peripheral devicesin power-conserving computer systems in which the central processingunit and other electronic components are powered down when theelectronic components are not needed.

BACKGROUND OF THE INVENTION

Advances in miniaturization of integrated circuits have led to theremarkable miniaturization of computer systems. Room-sized mainframecomputers of the 1950s gave way to large, cabinet-sized mainframe andmini-computers of the 1960s and 1970s. The personal computers thatemerged during the 1980s today provide, in a desk-top system, greatercomputing capacity than large mainframe or mini-computers from precedingdecades. In the 1990s, personal computers have been further miniaturizedto produce portable, convenient laptop computers powered by batteries.High-end laptop computers currently approach the performance of high-enddesktop systems. The increase of battery capacity through technologicalinnovation has not, however, kept pace with the increase in the densityof integrated circuits and concomitant miniaturization of computersystems. Although newer active matrix display screens and low-resistancepin connection technologies have helped to lower the power consumptionof laptop computers, and thereby extend the length of time during whicha laptop computer can operate using the available battery capacity, theusefulness of laptop computers is limited by limitations in batterycapacity.

Manufacturers have adopted a variety of strategies for conserving theuse of electrical energy stored in the batteries of laptop computers.Newer laptop computers employ power management strategies in whichunused components are detected and automatically powered down orsuspended until they are again required for operation of the computer.For example, the display screen of modern laptop computers isautomatically powered down after a period of quiescence. Similarly, thecentral processing unit ("CPU") of a modem laptop computer is powereddown, or suspended, when the computer has not executed any applicationprograms or processed any input or output activities for some period oftime.

As with desktop personal computers, laptop computers are being used withincreasing frequency not only for executing application programs, butalso as a platform for viewing and listening to multimedia presentationsand entertainment programs. The CD-ROM drive included with most laptopcomputers and desktop computers can be used, for example, to playbackrecorded music CDs through loud speakers attached to the laptop ordesktop computer. Playback of recorded music CDs (audio CDs) is commonlyimplemented through software application programs executed by the CPU.In many current systems, the CPU remains in a powered-on state while theCD-ROM drive is being used for playback of an audio CD. Because the CPUconsumes power at a high rate, use of a laptop computer for playback ofrecorded music CDs is quite limited by battery capacity. A large portionof the power consumed during playback of recorded music in thesecomputer systems is dissipated as heat from the CPU performing largelyunused instructions cycles. A need has therefore been recognized bymanufacturers of laptop computers to more effectively manage powerconsumption during playback of an audio CD on a laptop computer when theCPU of the laptop computer is otherwise not being used to either executeapplication programs or to control the CD-ROM drive.

SUMMARY OF THE INVENTION

One embodiment of the present invention provides a method to controloperation of a peripheral device attached to a power-conserving computersystem using electro-mechanical switches. The CPU of thepower-conserving computer system is powered-on, as necessary, totranslate user input through the electro-mechanical switches intocommands that the CPU then transmits to the peripheral device. When theCPU and other electronic components of the power-conserving computersystem are no longer required for operation of the peripheral device,the CPU and other electronic components are powered down, or suspended,by the power management component of the power-conserving computersystem while the peripheral device continues to perform the commandstransmitted to it. Powered-down electronic components are electricallyisolated from the peripheral device during operation of the peripheraldevice.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a conventional power-conserving laptopcomputer.

FIG. 2 is a block diagram of a power-conserving laptop computer inaccordance with one embodiment of the invention.

FIG. 3 is a flow control diagram of a BIOS power-up/reset routinemodified to implement the embodiment shown in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a user of a power-conserving computersystem with the ability to directly operate a peripheral device attachedto the power-conserving computer system. In the embodiment discussedbelow, a user of a power-conserving laptop computer is provided with theability to directly control the playback of audio CDs by the CD-ROMdrive included in the laptop computer. The technique of the presentinvention can be applied in other types of power-conserving computersystems for operation of a number of different types of peripheraldevices.

One strategy for conserving power in a computer system is to power downor suspend the CPU and other electronic components of the computersystem when it can be determined that the electronic components are notcurrently needed by a user. In the embodiment described below, a useroperates the CD-ROM drive in order to play audio CDs by inputtingvarious playback commands through electro-mechanical push-buttonswitches connected to the power management micro-controller within thelaptop computer. The power management micro-controller then transmitsthe playback commands to the core logic and CPU via an SM bus. When theCPU is powered-on for execution of other tasks, the CPU can respond touser playback commands entered via the push-button switches by directingcorresponding commands to the CD-ROM drive. When the CPU is in apowered-down, or suspended state, the power management micro-controllerpowers up the CPU which then begins executing a basic input/outputsystem (BIOS) power-up routine. The power-up routine detects when thepower-up was initiated because of user input to the push-button switchesthat control playback of audio CDs by the CD-ROM drive, determines whichplayback command was input by the user, and accordingly forwards one ormore appropriate commands to the CD-ROM drive to initiate the playbackoperation desired by the user. The power-up routine then issues aPower-CPU-Down command to the micro-controller so that the CPU isre-suspended or powered down by the micro-controller while the CD-ROMdrive performs the command. In this way, power that would be otherwisewasted by the CPU executing unneeded instructions while the CD-ROM driveperforms the command is, instead, conserved.

FIG. 1 is a block diagram of the relevant components of a conventionalpower-conserving laptop computer 100. The computer 100 includes a CPU102 executing instructions that compose software application programs,operating system routines, and low-level device driver routines thatcontrol the operation of peripheral devices. The instructions thatcompose software routines are stored in a random access memory ("RAM")104 and are fetched by the CPU 102 via a memory bus 106, a systemcontroller 108, and a CPU bus 110. A power management micro-controller112 is responsible for powering up and powering down the CPU 102, thesystem controller 108, and other electronic components so that thepower-conserving laptop computer 100 is responsive to user input, butdoes not idly waste valuable electrical energy stored in batteriesconnected to the laptop computer by maintaining unused electroniccomponents in a powered-on state. The power management micro-controller112 is connected to the system controller 108 via a two-wire,bi-directional SM bus 114 that allows the power managementmicro-controller 112 to transmit and receive information to and from theCPU 102 via the system controller 108. The power managementmicro-controller 112 is additionally connected, via connection 118, to apower supply 116 that provides electrical power to both the CPU 102 andsystem controller 108. When the power management micro-controller 112asserts the CPU ON/OFF output signal low through the connection 118, thepower supply 116 provides power to the CPU 102.

A CD-ROM drive 120 is connected to the system controller 108 through abus 122. The CD-ROM drive 120 contains a digital signal processor("DSP") 124 that converts photoelectronic data read from a CD rotatingwithin the CD-ROM drive 120 to digital data communicated to the systemcontroller over the bus 122. The CD-ROM drive 120 additionally containsa digital-to-analog converter 148 that produces an analog signal from anaudio CD that can be amplified and broadcast through loud speakers (notshown) attached to the laptop computer 100. The system controller 108may also be connected to additional peripheral devices (not shown) byanother bus 126, or, alternatively, through the bus 122 thatinterconnects the system controller 108 and the CD-ROM drive 120. Adisplay screen 128 is connected to the system controller 108 by a bus126.

The power management micro-controller 112 is supplied with electricalpower through a separate power supply 130. The CD-ROM drive 120 issupplied with electrical power from a power supply 132, and the displayscreen 128 is supplied with electrical power from a power supply 134.The power management micro-controller 112 is connected to the powersupplies 132 and 134 through signal lines 136 and 138, respectively. Thepower supplies 116, 130, 132, and 134 provide power to the CPU 102, thepower management micro-controller 112, the CD-ROM drive 120, and thedisplay screen 128 via connections 140, 142, 144, and 146, respectively.Alternatively, the four separate power supplies 116, 130, 132, and 134shown in FIG. 1 could be replaced by a single power supply with switchedoutputs.

In the conventional power-conserving laptop computer 100 diagrammed inFIG. 1, low-level software routines that control the laptop computer 100when it is powered-on can determine when the CPU 102 has been idle for acertain period of time and cause the CPU 102 to issue a power-CPU-downcommand to the power management micro-controller 112 via the CPU bus 110and the SM bus 114. The power management micro-controller 112 thenpowers down the CPU 102, the system controller 108, and othertemporarily unneeded electronic components in order to conserveelectrical energy. In similar fashion, the display screen 128 can bepowered down by the power management micro-controller 112 when thelow-level software routines determine that what is being displayed onthe display screen have not changed for some period of time.

Software application programs have been developed to allow a user toplay back recorded music from an audio CD using the CD-ROM drive. A usermay invoke such a program and, by some input or combination of inputsvia a keyboard, a mouse, and a graphical user interface displayed on thedisplay screen, direct the program to play an audio CD. From a powerconservation standpoint, it would be desirable to immediately power downthe CPU 102 once the CD-ROM drive 120 begins playing back the recordedmusic. Once the CPU 102 has issued a start-playing command to the CD-ROMdrive 120 in response to user input, the CPU 102 is no longer neededuntil the user inputs an additional playback command. Furthermore, itwould be desirable for the computer user to initiate playback of anaudio CD through some means other than invoking a software applicationprogram and inputting commands through a graphical user interfacedisplayed on the display screen. If it were possible for a user to issueplayback commands more directly to the CD-ROM drive 120, power would beconserved because most of the electronic components of the laptopcomputer 100 would not need to be powered-on. The CPU 102 and systemcontroller 108 would need to be powered-on only for a brief period oftime preceding transmission of a command from the CPU 102 to the CD-ROMdrive 120 in response to a user-input playback command. Conventionalpower-saving laptop computers 100 may eventually detect that neither theCPU 102 nor the display screen 128 are required after some periodfollowing initiation of a playback command, but a great deal of power isconsumed in the interim, and, in the case of the display screen 128,power-up could be avoided completely if a graphical user interface werenot required.

FIG. 2 is a block diagram of a power-conserving laptop computer 200 inaccordance with one embodiment of the invention. The majority of thecomponents shown in FIG. 2 are identical to the components shown inFIG. 1. Thus, in the interest of brevity, those components of FIG. 2that are identical to components in FIG. 1 have been provided with thesame reference numerals as in FIG. 1, and an explanation of theiroperation will not be repeated.

Several additional components have been added to the computer 200 shownin FIG. 2. These include electro-mechanical pushbutton switches 202 thatallow a computer user to activate the CD-ROM drive 120 in order tocontrol playback of an audio CD, similar to the PLAY, STOP, and SKIPpushbuttons on conventional audio CD players. Additional inputs 204,including an input for volume control, have also been added. Inputs 202and 204 are connected to the power management micro-controller 112. Thebus 122 connecting the CD-ROM drive 120 with the system controller 108is, in this embodiment, an AT Attach Packet Interface bus, and aquickswitch buffer 206 has been added to prevent current leakage fromthe CD-ROM drive 120 to the system controller 108 when the CD-ROM drive120 is operating and the system controller 108 is not powered-up. An ORgate 208 has been added to control the buffer 206. When the CPU ON/OFFoutput 118 from the power management micro-controller 112 is assertedlow causing the CPU 102 to be powered-on, and when the OE output 212 ofthe system controller 108 is asserted low, then the OE input 214 to thequickswitch buffer 206 is also asserted low and data can flow betweenthe CD-ROM drive 118 and the system controller 108. Otherwise, the OEinput 214 to the quickswitch buffer 206 is deasserted high and thesystem controller is isolated from the CD-ROM drive.

When a user activates one of the input devices 202 or 204, the powermanagement micro-controller 112 communicates the user's input via thesystem controller 108 to the CPU 102, which then transmits anappropriate command to the CD-ROM drive 120. If the CPU 102 has beenpowered down, then the power management micro-controller 112 firstpowers on the CPU 102 which then receives the user's input to an inputdevice 202 or 204 from the power management micro-controller 112,transmits an appropriate command to the CD-ROM drive 120, and thenrequests that the power management micro-controller 112 power down theCPU 102 in order to conserve energy. The input devices 202 and 204 aresufficient to allow the user to control playback of an audio CD in thesame manner that playback of an audio CD is controlled on a conventionalCD player. The display screen 128 need not be in a powered-on state forplayback of an audio CD. Thus, the battery power supply is conserved bynot powering idle operation of the CPU 102 and display screen 128 whilethe CD-ROM drive 120 plays an audio CD. Unlike in the conventionalsystem shown in FIG. 1, in this embodiment of the present invention, theCPU 102 is powered-on only for the amount of time required to receive aninput from the user through an input device 202 or 204 and transmit anappropriate command to the CD-ROM drive 120.

Thus, in the power-conserving laptop computer embodiment shown in FIG.2, the added electro-mechanical input switches 202 and 204 provide foruser input directly to the CD-ROM drive 120 without the need for asoftware application program running on the CPU 102 or a graphical userinterface displayed on the display screen 128. The added logic circuitprovides for isolation of the system controller 108 from the CD-ROMdrive 120 when the CD-ROM drive 120 is operating to play an audio CD andthe CPU 102 is powered down or suspended to conserve electrical energystored in the laptop computer's battery (not shown). A third differencebetween the embodiment shown in FIG. 2 and the conventional laptopcomputer shown in FIG. 1 resides in the BIOS power-up/reset routineinitially stored, in both systems, in read-only memory and transferredto the RAM 104 for execution by the CPU 102.

FIG. 3 is a flow control diagram of a BIOS power-up/reset routinemodified to implement the embodiment shown in FIG. 2. The BIOSpower-up/reset routine is invoked when the CPU 102 is reset orpowered-on by the power management micro-controller 112. In step 301,the BIOS power-up/reset routine checks the status of theelectro-mechanical input devices 202 and 204 as reported by the powermanagement micro-controller 112 over the SM bus 114. If the BIOSpower-up/reset routine determines, in step 304, that a user has input aplayback command through input devices 202 or 204, control flows to step306. If the user has not input a playback command through input devices202 and 204, the BIOS power-up routine calls the conventional, ornormal, power-up/reset routine in step 308 and then returns. If aplayback command has been input by a user, then, in step 306, the BIOSpower-up/reset routine checks the status of the CD-ROM drive 120 bysending a command to the CD-ROM drive 120 and receiving a response fromthe CD-ROM drive via the ATAPI bus 122, system controller 108, and theCPU bus 110. If the BIOS power-up/reset routine determines, in step 310,that an audio CD has been mounted in the CD-ROM drive, control flows tostep 312. If the CD-ROM drive does not contain an audio CD, then, instep 314, the BIOS power-up/reset routine issues a Power-All-Downcommand to the micro-controller and then returns. The Power-All-Downcommand causes the power management micro-controller 112 to power downany of the electrical components of the laptop computer 200 that are inthe powered-up state, other than the CD-ROM drive 120 and componentsrequired to playback an audio CD. This is done because only audio CDscan be played via the input controls 202 and 204. Otherwise, if adigital data-containing CD is mounted in the CD-ROM drive 120, then thatdata must be accessed under control of the CPU 102 running operatingsystem device driver routines. If an audio CD is mounted in the CD-ROMdrive 120, then in step 312, the BIOS power-up/reset routine determinesthe appropriate command to issue to the CD-ROM drive in order to causethe CD-ROM drive to perform the operation designated by the user asinput to the input devices 202 and 204. If the BIOS power-up/resetroutine detects, in step 316, that the command issued in 312 correspondsto a STOP command, then, in step 318, the BIOS power-up routine issues aPower-CPU-Down command to the power management micro-controller 112 sothat the CPU 102, the system controller 108, and other temporarilyunnecessary components are immediately powered down and preciouselectrical energy is not used to maintain the CPU in an idle runningstate, after which the BIOS power-up/reset routine returns.

Although the present invention has been described in terms of oneembodiment, it is not intended that the invention be limited to thisembodiment. Modification within the spirit of the invention will beapparent to those skilled in the art. For example, the power managementmicro-controller 112, shown as a separate electronic component in FIGS.1 and 2, may instead be incorporated into the system controller 108 orsome other integrated circuit within the computer. Different types ofbuses may be used, and a variety of different connectivity topologiesmay be employed to produce an embodiment of the present invention. Adifferent type of input system, other than electro-mechanicalpush-button switches, may be used to provide the user with the abilityto directly control the CD-ROM drive. Other types of peripheral devicesmight be similarly included in the laptop computer, similarly directlyinterfaced, similarly isolated with a buffer, and similarly controlledthrough the power management micro-controller, system controller, andCPU. Different types of power management strategies may be accommodated.For example, the power management system may be able to anticipate theprobable timing of subsequent events requiring the CPU to be powered-upand therefore place the CPU in a ready state at precisely the time theCPU is needed to perform further operations. The present invention maybe employed in computer systems other than laptop computers, and may beemployed for purposes other than power conversation. The scope of thepresent invention is defined by the claims that follow.

What is claimed is:
 1. A method for operating a peripheral device on a computer system having a CPU and the peripheral device, the method comprising:detecting a user-level command to change the operation of the peripheral device which the peripheral device is operating; determining whether the CPU is powered down, the CPU being operable in either a powered down mode or a powered up mode; in response to detecting the user-level command when the CPU is determined to be powered down, powering up the CPU; transmitting a peripheral device command responding to the user-level command from the CPU to the peripheral device; after transmitting the selected peripheral device command from the CPU to the peripheral device, powering down the CPU; and executing the peripheral device command using the peripheral device without receiving additional input or control signals from the CPU.
 2. The method of claim 1 wherein the computer system further includes a system controller through which the peripheral device command is transmitted from the CPU to the peripheral device, the method further comprising electronically isolating the peripheral device from the system controller while the peripheral device is executing the peripheral device command.
 3. A method for planing an audio CD on a computer system having a CPU and an audio disk drive, the method comprising:detecting a user-level command to alter the playing of the audio CD on the audio disk drive while the audio CD is playing; determining whether the CPU is powered down, the CPU being operable in either a powered down mode or a powered up mode; in response to detecting the user-level command to change the operation of the audio disk drive when the CPU is determined to be powered down, powering up the CPU; transmitting a disk drive command corresponding to the user-level command from the CPU to the audio disk drive; powering down the CPU; and executing the disk drive command without receiving further input or control signals from the CPU.
 4. The method of claim 3 where in a user-level command to alter the playing of the audio CD may include commands to start playing the audio CD and to stop playing the audio CD.
 5. The method of claim 3 where in the computer system further includes a system controller through with the disk drive command to alter the playing of the audio CD is transmitted from the CPU to the audio disk drive, the method further comprising electronically isolating the audio disk drive from the system controller while the audio disk drive is executing the disk drive command.
 6. The method of claim 3 wherein the audio disk drive comprises a CD-ROM drive.
 7. The method of claim 4 wherein a user-level command to alter the playing of the audio CD may further include commands to pause from playing the audio CD, to skip forward on the audio CD, and to skip backward on the audio CD.
 8. A method for playing an audio CD on a computer system having a CPU and a CD-ROM drive, the method comprising:receiving an indication of input of a user-level command to change the operation of the CD-ROM drive while CD-ROM drive is operating; determining whether the CPU is initially powered down, the CPU being operable in either a powered down mode or a powered up mode; when the CPU is determined to be initially powered down, powering up the CPU; using the CPU to select a CD-ROM command corresponding to the user-level command; transmitting the selected CD-ROM command corresponding to the user-level command to the CD-ROM drive; when the CPU is determined to be initially powered down, powering down the CPU; and executing the selected CD-ROM command on the CD-ROM drive.
 9. The method of claim 8, further comprising:when powering up the CPU, executing a power-up routine on the CPU that selects the CD-ROM command corresponding to the user-level command, causes the selected CD-ROM command corresponding to the user-level command to be transmitted to the CD-ROM drive, and causes the CPU to be powered down.
 10. The method of claim 9 wherein a user-level command to change the operation of the CD-ROM drive may include commands to start playing the audio CD and to stop playing the audio CD.
 11. The method of claim 9 wherein the computer system further includes a system controller through which the CD-ROM command to change the operation of the CD-ROM drive is transmitted from the CPU to the CD-ROM drive, the method further comprising electronically isolating the CD-ROM drive from the system controller while the CD-ROM drive is executing the CD-ROM command.
 12. The method of claim 10 wherein a user-level command to change the operation of the CD-ROM drive may further include commands to pause from playing the audio CD, to skip forward on the audio CD, and to skip backward on the audio CD.
 13. A method for conserving power usage in a computer used to operate a peripheral device, the computer having electronic components including a CPU, a system controller, and an attached peripheral device, the method comprising:detecting unused electronic components, including the CPU, and powering the unused components down, the CPU being operable in either a powered down mode or a powered up mode; and when the CPU is powered down and an indication is received of the input of a command to change the operation of the peripheral device while the peripheral device is operating,powering up the CPU, using the CPU to select a peripheral device command corresponding to the command to change the operation of the peripheral device, transmitting the selected peripheral device command corresponding to the command to change the operation of the peripheral device to the peripheral device, powering down the CPU, and executing the selected peripheral device command on the peripheral device.
 14. The method of claim 13, further including electronically isolating the system controller from the peripheral device while the peripheral device executes the peripheral device command.
 15. The method of claim 13, further comprising:when the CPU is powered on and an indication is received of the input of a command to change the operation of the peripheral drive,selecting a peripheral device command corresponding to the command to change the operation of the peripheral drive, transmitting the selected peripheral device command corresponding to the command to change the operation of the peripheral drive to the peripheral, and executing the selected peripheral device command on the peripheral device.
 16. A method for conserving power usage in a computer used to play an audio CD, the computer having electronic components including a CPU, a system controller, and a CD-ROM drive, the method comprising:detecting unused electronic components, including the CPU, and powering the unused components down, the CPU being operable in either a powered down mode or a powered up mode; and when the CD-ROM drive is operating and the CPU is powered down and an indication is received of the input of a user-level command to change the operation of the CD-ROM drive,powering up the CPU, using the CPU to select a CD-ROM command corresponding to the user-level command, transmitting the selected CD-ROM command corresponding to the user-level command to the CD-ROM drive, powering down the CPU, and executing the selected CD-ROM command on the CD-ROM drive.
 17. The method of claim 16, further including electronically isolating the system controller from the CD-ROM drive while the CD-ROM drive executes the CD-ROM command.
 18. The method of claim 16, further comprising:when the CPU is powered on and an indication is received of the input of a user-level command to change the operation of the CD-ROM drive,selecting a CD-ROM command corresponding to the user-level command, transmitting the selected CD-ROM command corresponding to the user-level command to the CD-ROM drive, and executing the selected CD-ROM command on the CD-ROM drive.
 19. A method for conserving power usage in a computer used to operate autonomous and dependent peripheral devices, the computer having electronic components including a CPU, a system controller, an autonomous peripheral device, and a dependent peripheral device, the autonomous peripheral device able to execute a command received from the CPU without further interaction with the CPU, the dependent peripheral device requiring further interaction with the CPU in order to execute a command received from the CPU, the method comprising:when a peripheral device is operating and the CPU is powered down and an indication is received of input of a command to change the operation of the peripheral device,powering up the CPU, the CPU being operable in either a powered down mode or a powered up mode, using the CPU to select a target peripheral device and a peripheral device command corresponding to the command to change the operation of the peripheral device, transmitting the selected peripheral device command corresponding to the command to change the operation of the peripheral device to the target peripheral device, when the target peripheral device is the autonomous peripheral device, powering down the CPU, and executing the selected peripheral device command on the target peripheral device.
 20. The method of claim 19 further including electronically isolating the system controller from the target peripheral device while the target peripheral device executes the peripheral device command.
 21. The method of claim 19 further comprising:when the CPU is powered on and an indication is received of input of a command to change the operation of the peripheral drive,using the CPU to select a target peripheral device and a peripheral device command corresponding to the command to change the operation of the peripheral drive to the target peripheral device, and executing the selected peripheral device command on the peripheral device. 